DETAILED FLOW
- COLLECT THE INFORMATION FROM THE CUSTOMER It is also important to clarify customer complaints before inspection. First of all, reproduce symptoms and understand them fully. Ask customer about his/her complaints carefully. In some cases, it is necessary to check symptoms by driving vehicle with customer. CAUTION: Customers are not professional. It is dangerous to make an easy guess like "maybe the customer means that...," or "maybe the customer mentions this symptom". : GO TO 2.
- CHECK THE STATUS Power steering fluid leakage and check the power steering fluid level. Refer to " «INSPECTION»(ref-617004-S34960068692014052000000) ". Check the drive belt tension. Refer to " «CHECKING»(ref-616997-S39338073452014052000000) ". Check the power steering gear for damages, cracks and fluid leakage. Refer to " «2WD: INSPECTION»(ref-617004-S18174168012014052000000) " (2WD models), " «AWD: INSPECTION»(ref-617004-S33797639382014052000000) " (AWD models). Check the relief oil pressure. Refer to " «INSPECTION»(ref-617004-S30531527722014052000000) ". : GO TO 3.
- DIAGNOSIS CHART BY SYMPTOM Perform the diagnosis by symptom. Refer to " «DIAGNOSIS PROCEDURE»(ref-617054-S07042515552014052000000) ". : GO TO 4.
- FINAL CHECK Check the input/output standard values for the power steering control unit. Are the power steering control unit input/output values within standard ranges respectively? YES: INSPECTION END NO: GO TO 2 .
Scheme 5
Scheme 5: CONTROL DIAGRAM
Scheme 6
Scheme 6: CROSS-SECTIONAL VIEW
Scheme 7
Scheme 7: System Description
- The EPS system controls the power steering solenoid valve through the power steering control unit.
- The valve driving voltage to control the power steering solenoid valve varies according to the vehicle speed.
Scheme 8
Scheme 8: During Parking (When Turning The Steering Wheel To The Right.)
- Power steering solenoid valve is closed while a vehicle is stopped.
- Pinion "1R", "2R" and "3R" are closed depending on steering torque of steering wheel.
- Oil pressure "P" in the gear housing assembly is the sum of oil pressures occurred in "2R" and "3R". This results in a light steering force because of high pressure.
Scheme 9
Scheme 9: During High-speed Operation
- Power steering solenoid valve is opened during high-speed operation.
- Pinion "1R", "2R" and "3R" are closed depending on steering torque of steering wheel.
- Oil pressure "2R" does not occur because the power steering solenoid valve is on full throttle.
- Oil pressure "P" in the gear housing assembly includes only oil pressure occurred in "3R" and results in a heavy steering force.
Scheme 10
Scheme 10: Component Parts Location
Component Function Check
- CHECK POWER STEERING SOLENOID VALVE OPERATION Check changes in steering force from a halt condition to high-speed driving. Is the inspection result normal? YES: INSPECTION END NO: Check the power steering solenoid valve. Refer to " «DIAGNOSIS PROCEDURE»(ref-617054-S13686750592014052000000) ".
PHYSICAL VALUES
Terminal No. (Wire color) Description Condition Value (Approx.) + - Signal name Input/Output 1 (LG) Ground Power steering solenoid valve voltage Output Vehicle speed: 0 km/h (0 MPH) (Engine is running) 4.4 - 6.6 V Vehicle speed: 100 km/h (62 MPH) 2.4 - 3.6 V 3 (G) Ground Ignition switch power supply Input Ignition switch: ON Battery voltage Ignition switch: OFF 0 V 5 (B) Ground Power steering solenoid valve ground - Always 0 V 6 (B) Ground Ground - Always 0 V 8 (L) Ground Vehicle speed signal Input Vehicle speed: 40 km/h (25 MPH) CAUTION: Check air pressure of tire under standard condition. 10 (R) Ground Engine speed signal Input Engine is running Warm-up condition Idle speed Engine is running Warm-up condition Engine speed: Approx. 2, 000 rpm
| CAUTION | When using circuit tester or oscilloscope to measure voltage for inspection, be sure not to forcibly extend any connector terminals. |
Scheme 11
Scheme 11: Wiring Diagram - ELECTRONICALLY CONTROLLED POWER STEERING SYSTEM
Scheme 12
Scheme 12: Connector Terminal Identification
Scheme 13
Scheme 14
Scheme 15
- EPS system enters the fail-safe mode (that allows the steering force to be controlled without impairing the driveability) if any of the input/output values to/from EPS system (power steering control unit) deviate from the standard range. NOTE: The system enters the fail-safe mode if the engine speed remains at 1, 500 rpm or more for over 10 seconds while the vehicle is stopped. This is normal.
- The fail-safe function is canceled when a vehicle speed signal of 2 km/h (1.2 MPH) or more is inputted or the ignition switch is turned OFF-->ON. EPS system restores the normal operation at that time.
| Mode | Warning lamp | DTC | Detection point (malfunction part) | Error area and root cause |
|---|
| Fail-safe function | | | Vehicle speed signal input | Engine speed is 1, 500 rpm or more and there is no vehicle speed signal input for over 10 seconds during vehicle travel. Vehicle speed signal has abruptly dropped from 30 km/h (19 MPH) or more to 2 km/h (1.2 MPH) or less within 1.4 seconds. |
Precaution for Supplemental Restraint System (SRS) "AIR BAG" and "SEAT BELT PRE-TENSIONER"
The Supplemental Restraint System such as "AIR BAG" and "SEAT BELT PRE-TENSIONER", used along with a front seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain types of collision. Information necessary to service the system safely is included in the " SRS AIRBAG " and " SEAT BELTS " articles of this Service Information.
| WARNING | Always observe the following items to prevent accidental activation. To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death in the event of a collision that would result in air bag inflation, all maintenance must be performed by an authorized NISSAN/INFINITI dealer. Improper maintenance, including incorrect removal and installation of the SRS, can lead to personal injury caused by unintentional activation of the system. For removal of Spiral Cable and Air Bag Module, see " SRS AIRBAG ". Never use electrical test equipment on any circuit related to the SRS unless instructed to in this Service Information. SRS wiring harnesses can be identified by yellow and/or orange harnesses or harness connectors. |
PRECAUTIONS WHEN USING POWER TOOLS (AIR OR ELECTRIC) AND HAMMERS
| WARNING | Always observe the following items for preventing accidental activation. When working near the Air Bag Diagnosis Sensor Unit or other Air Bag System sensors with the ignition ON or engine running, never use air or electric power tools or strike near the sensor(s) with a hammer. Heavy vibration could activate the sensor(s) and deploy the air bag(s), possibly causing serious injury. When using air or electric power tools or hammers, always switch the ignition OFF, disconnect the battery, and wait at least 3 minutes before performing any service. |
Scheme 16
Scheme 17
- Remove instrument lower cover. Refer to " «EXPLODED VIEW»(ref-617029-S40098201342014052000000) ".
- Remove glove box assembly. Refer to " «EXPLODED VIEW»(ref-617029-S40098201342014052000000) ".
- Remove instrument lower panel RH. Refer to " «EXPLODED VIEW»(ref-617029-S40098201342014052000000) ".
- Remove power steering control unit screws.
- Remove power steering control unit (1).
- Disconnect power steering control unit connector.
